Copper alone is not enough

Abstract: Downy mildew is one of the most devastating diseases in viticulture worldwide. In
organic viticulture, the disease is mainly controlled with copper-containing fungicides.
However, these fungicides have several disadvantages, such as low rain stability. Furthermore, they provide no protection for newly grown leaf area and are less effective on clusters. In the search for suitable alternatives or possible supplements to existing copper products, field trials have been carried out as part of several research projects. To this end, various basic substances, as well as sulfur and potassium phosphonate were tested for their effectiveness against downy mildew. However, only sulfur and potassium phosphonate offered sufficient efficacy at high infection pressure.